I'm planning on travelling out of the country and will bring my iPhone along. There will be WiFi access at my destination and I only intend on planning on using my iPhone for that. Is there anyway to sever all communications (data and voice) with the cell tower and keep WiFi connectivity?

These are listed in the most true to your initial intent of not having the antenna operating. I like the middle one as a good tradeoff between not talking with cell towers but maintaining GPS capabilities to tag pictures and use the map with tiles present from WiFi. The battery drain on the second two are more than the first, but still pretty usable in general on the later iOS versions.

Clearly, you can't pull a SIM if you have a phone without one, but the other options work with all iPhone models.